The base frame: 2x8s. The skinny bed is the path.
It’s going to take a couple of posts, but I wanted to show you the process of building a greenhouse (hoophouse, polytunnel, etc.) for my mom. It’s a 10’x12′ complete kit from Growers’ Solution. We’re doing two major beds in it with one long path down the middle (30″ wide x 12′ long). This means the beds themselves are fairly deep at 3′-6″. She understands that weeding will be, literally, a stretch, but she’s not concerned. She’ll have 84 square feet of space under plastic to grow things, so, what’s a little stretching?
On the fated day, Easter, that our daughter went into the hospital, I was playing Mother of the Year by actually building my own mother’s greenhouse’s base frame. (I suppose that makes me Daughter of the Year.) I used untreated 2×8 members: short side (where the door is) are 10′ long, long sides and inner beds 12′. They’re held together with galvanized lag screws with washers that are 3″ x 1/4″. We assembled it on a flat surface (the driveway) then picked it up and moved it to where my mom wants it. It wasn’t heavy; two people can lift it easily.
My mom and brother have removed all the grass in the beds. As a precaution against all the moles tunneling in her sandy soil, they are going to bury some aluminum valley flashing (basically, thin metal) around the inside edges of the beds themselves so the little creatures cannot tunnel in. It will go down about 6″ below the soil line.
Tonight after work I will hammer in the ground posts (galvanized steel tubes that are 2″ in diameter, 30″ long), level them, then put together then assemble the hoop frames. I will likewise screw the hoops together on a level surface; it’s important to not have things too wonky. These hoops will go into the ground posts and get screwed into them with metal-tapping galvanized screws. This hoophouse is so small it only requires a center purlin; hopefully we’ll get that assembled and attached down the center too.
I always fall down on the photo-taking. Here we’ve erected the hoops and screwed them into the base poles. We leveled the hoops by connecting the top purlin to the front and back hoops, made it level, fastened those hoops to their posts then leveled and connected the middle two.
Tomorrow morning I hope to erect the end walls. These are made of 2x4s; I intend to frame the door at one end and just a simple frame at the other. (See the post below this one to see my own greenhouse’s end wall.) The plastic will have to wait until another day! Mom needs to get the topsoil/compost in place, and woodchips down the center aisle. Then, it’s planting time.
Here’s another example of hammering something out to suit your needs. This is a joist hanger/strap anchor. I wrapped it up and over the top of this 2×4. That’s the top of the greenhouse, top of the hoop you’re seeing. I chamfered/birdmouthed the top of the 2×4 to accept the hoop.